The present invention is directed to a ring interferometer having an optical waveguide wound in the coil and having two ends, each end providing a separate coupling location at which light from a source is coupled into the light waveguide and propagated to the opposite end for uncoupling. The interferometer will include an arrangement for superimposing the light output coupled from each end of the optical waveguide and creating two portions of superimposed output coupled light and an arrangement for directing at least one portion of the output coupled light at a first light receiving surface over a common path in a direction opposite to a direction of the light from said source.
A ring interferometer of the above described type represents an arrangement for determining non-reciprocal transit time differences. If the interferometer is at rest or in uniform translational movement relative to an inertial system, the light propagation both in the light waveguide and in the air passages is reciprocal. For example, the optical wavelength of the light path is precisely the same for both directions of the propagation of the light. It is known that all dielectric material, which are used to construct light waveguides and are either at rest or in uniform translational movement relative to an inertial system, must always behave in a reciprocal fashion in the absence of a magnetic field. In the construction of the ring interferometer, it has now been proved that unexpected non-reciprocal effects can be observed, which simulate an acceleration movement, for example a rotation movement, which differs from zero.